Crawl space types and building physics
Matilainen, M., Jerkku I. and Kurnitski, J.
1999
Finland, Helsinki University of Technology, Laboratory of Heating, Ventilating and Air Conditioning, Report B63, Espoo, 61 pp, in Finnish
crawl space, guidelines, ventilation strategy
Matilainen, M., Jerkku I. and Kurnitski, J., (1999), Crawl space types and building physics, Finland, Helsinki University of Technology, Laboratory of Heating, Ventilating and Air Conditioning, Report B63, Espoo, 61 pp, in Finnish.
| Abstract: |
| Different types of crawl spaces are listed and their physical behaviour including heat, moisture and air change is discussed. The objective was to collect information on the behaviour of crawl spaces, especially concerning moisture control and optimum air change. In addition, the results of two other reports are given in the form of preliminary guidelines for crawl spaces. The behaviour of ordinary crawl spaces ventilated naturally or mechanically by outdoor air as well as heated crawl spaces, unventilated crawl spaces and crawl spaces ventilated by indoor air are discussed. Preliminary guidelines are given for crawl spaces ventilated by outdoor air. Ground moisture evaporation and the crawl space temperature are the most critical factors affecting the moisture behaviour of a crawl space. If the ground moisture evaporation is not reduced by ground cover, the humidity of the crawl space will rise over the limits of mould growth. Properties of ground cover and calculation methods to assess moisture evaporation are given. Air change will affect both humidity and temperature in crawl space. The need for air change is discussed based on results from previous and the present research and some guidelines for optimum ventilation are given. The given guidelines are specific and include the control of roof-, surface- and ground water as a part of crawl space design. The guidelines are preliminary and will be revised in the second stage of the project. Publishing of preliminary guidelines is considered to be useful, as even a small improvement of the current situation might be a notable step ahead towards properly functioning crawl spaces.
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